Experimental study on mechanical and drying shrinkage properties of HECC with different mix proportions
Hydraulic Engineered Cementitious Composites(HECC)has the characteristics of medium strength,low elastic modu-lus,strong thermal stability,controllable crack width and wide source of raw materials.Because there is no coarse aggregate in HECC and the amount of cementitious material is high,the volumetric deformation of HECC is significantly higher than that of or-dinary hydraulic concrete,so the volumetric stability must be reasonably controlled.In order to explore the influence of different factors on the drying shrinkage and mechanical properties of HECC and their development rules,the flow performance,compres-sive and flexural strength and drying shrinkage performance tests of HECC under different water-binder ratio,fiber content,fly ash and silica fume content were carried out,and the hydration products were observed by SEM.The results showed that when the water consumption was constant,the water-binder ratio increased from 0.25 to 0.35,and the 28 d compressive strength,flexural strength and drying shrinkage decreased by17.3%,9.7%and20.5%,respectively.The fiber content significantly affected the flexural strength.The flexural strength of HECC with 2.0%fiber was 30.0%higher than that with 1.0%fiber,but it had little effect on compressive strength and dry shrinkage.The content of fly ash had a great influence on the compressive and flexural strength of HECC.The compressive and flexural strength decreased gradually with the increasing of fly ash.The compressive strength and flexural strength of HECC with 60%fly ash were 30.4%and 18.2%lower than those with 40%fly ash.The in-creasing of fly ash content can greatly reduce the drying shrinkage.The drying shrinkage of HECC with 60%fly ash was 23.5%lower than that of 40%fly ash.The addition of silica fume can improve the early compressive and flexural strength of HECC,and with the increase of silica fume content,the increasing trend gradually slowed down.However,the addition of silica fume was not conducive to the drying shrinkage of HECC,which would increase the drying shrinkage.The drying shrinkage of HECC with 6%silica fume was 13.6%higher than the reference group.
国家科技期刊平台
NSTL
万方数据
维普
